Conventional devices are described as follows, which detect electric signals developed in human body.
First, a device detecting electric signals of nerves, based on MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), was conventionally proposed. This prior art is a technique monitoring change of membrane capacitance depending on exterior stimuli by using gatings of MOSFET device, moreover a technique simultaneously monitoring various neural responses. This prior art has been applied to a method of detecting nerve signals by fixing positions of snail neurons around P-MOSPET with picket fences made of polyimide and culturing them with limiting mobility (Zeck et. al., Noninvasive neuroelectronic interfacing with synaptically connected snail neurons immobilized on a semiconductor chip, Proc Nat Acad Sci 2001; 98). FIG. 1 is represents intra-cellular signals and extra-cellular signals detected according to such first prior art.
Second, a technique for detecting electric stimuli of brain stems or nerve fibers was proposed. Normann group of University of Utah (USA) and Cyberkinetics have been proceeding a research to measure electric signals and stimulate nerves by directly inserting multi-electrodes in nerves and brains since 2000 (Normann et. al., Long-Term Stimulation and Recording With a Penetrating Microelectrode Array in Cat Sciatic Nerve, IEEE Transactions on Biomedical Engineering, VOL. 51, NO. 1, JANUARY 2004). FIG. 2 represents multi-electrodes according to the second prior art and a shape that these electrodes are inserted in cat sciatic nerve.
Third, a technique inserting sieve electrodes in nerve fibers was proposed. Through joint researches of Fraunhofer-IBMT (Germany), IMTEK (Germany) and the like, regeneration of nerve has been studied and recording of nerve signals is attempted, by inserting sieve electrodes to be curved, in nerve fibers and transmitting electric stimuli thereto (Anup et. al., Design, in vitro and in vivo assessment of a multi-channel sieve electrode with integrated multiplexer, J. Neural Eng. 3 (2006) 114-24). FIG. 3 represents the sieve electrodes based on the third prior art as described above. Total diameter of the sieve is the same as that of rat sciatic nerve (1.5 mm), and 571 holes having a diameter of 40 μm are disposed therein at 70 μm intervals. In addition, electrodes of ring shape cover 27 holes and their area is 2200 μm2.